Known prior art engine clip bolts are disclosed in U.S. Pat. No. 4,974,274 granted Dec. 4, 1990, and entitled "Method of Making an Engine Clip Bolt"; in U.S. Pat. No. 5,092,723 granted Mar. 3, 1992, and entitled "Engine Clip Bolt"; and in U.S. Pat. No. 3,451,456 granted Jun. 24, 1969, and entitled "Bolt with Restrainer."
The '456 patent discloses a bolt with a rotation restraining clip secured to the head of the bolt either by (1) three rivets which are integral with the head of the bolt and which extend through three mating holes in the clip, or by (2) a bolt with a square rivet shank extending through a square opening in the clip, with the corners of the rivet shank riveted over the clip.
The disclosures of the '274 and the '723 patents are substantially the same, and involve the provision of a clip with a scalloped opening and a bolt with a cylindrical protrusion on its head which initially extends through the scalloped hole in the clip and which is orbitally swaged outward into the scalloped recesses and over the entire opening of the clip. This configuration is intended to hold the clip in place onto the bolt, even if the clip rotates relative to the bolt, to avoid possible damage to associated equipment that could be caused by a loose clip. The patent files associated with the '274 and '723 patents define the term "scalloped" as "having a wavy edge, border or design," and a "scallop" as "one of a series of rounded projections . . . "
The '274 and '723 patents use an orbital swaging machine to swage the cylindrical protrusion into the scalloped recesses. This is a relatively expensive and time-consuming process, as an orbital swaging machine may cost about $30,000, and the orbital swaging process requires the substantial interval of time needed to advance the swaging tool as it is being rotated.